Combination roller coaster wheel

ABSTRACT

Wear resistant metal ring thermally locked at a machined interface to a lightweight alloy roller coaster wheel body and method of machining and thermally locking.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a division of co-pending U.S. Ser. No. 12/914,049filed Oct. 28, 2010, the entire contents of which are herebyincorporated by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to roller coaster wheels.

2. Description of the Prior Art

Roller coasters have for centuries been a popular form of entertainmentand distraction in nearly every developed country, starting in about the17^(th) century with the ice slides in Russia involving the frame workconstructed of the lumber with several inches of thick ice covering thesurface so that sliders could speed down the 50° drop. By the mid tolate 1700's wheels had been added to roller coaster cars and as designimprovements continued, methods where devised for locking the cars untothe tracks and for guiding the cars along the tracks and the applicationof the brakes for slowing the speed of the car. After some slackening,wooden frame roller coasters have now regained their popularity, growingto over 3,000 feet in length and some 70°-75° and beyond in the firstdrop with undulations providing for fast to slow and back to fastseveral times throughout the course with twisting layouts andchallenging contours providing for good, violent rides.

Many installations provide trains of cars including multiple wheels oneach car which may involve 80 to 100 wheels per roller coaster train.The wheels are subjected to high stresses and strain throughout themaneuvers of the roller coaster trains while they experience changes inangular acceleration as they wind along their paths, through curves,variations in elevation and positive and negative G's, repetitivelystressing the wheels and applying high loads thereto. The wheels mayhave an outside diameter on the order of 4 to 12 inches and the treadsurfaces thereof are typically in direct contact with the tracks oftenmaking metal to metal contact and experiencing the abrasive effect ofdirt or grit captured between the wheels and the tracks and therepetitive pounding of metal on metal which, in spite of shock absorberssometimes incorporated in the vehicles, tends to shock the wheels andshorten their service lives. Efforts have been made to smooth out trackinstallations in effort to reduce the loads and fatigue on the wheelsbut this is generally an imperfect construction and maintenance process.It is also been proposed to incorporate plastic tread in the form ofurethanes and the like in effort to absorb the shock and extend the lifeof the wheels but, such treads typically wear relatively rapidlyresulting in high maintenance expenses for replacement and repair.

Those working in the art have recognized that steel wheels, whileproviding structure and integrity, are extremely expensive and littleflex or give which might absorb the high impact shock applied to thewheels. In other areas of wheel design, numerous different constructionshave been proposed to provide hard, impact resistant tread surfaces. Anearly examples is wooden or cast wheel bodies having a circularperiphery about which was formed a wear and shock resistant tread band.One of the challenges addressed has been the efficient and positiveattachment of the band to the wheel in effort to resist shock,separation and wear and tear to provide for a long life. One suchsolution was to provide a strip of steel to be bent in a circle aboutthe wheel body to bring the opposite ends into confronting spacedrelationship exhibiting a small gap so that the band could be heated toprovide thermal expansion and closure of the gap for welding or otherattachment to hold the band closed so that, upon cooling it wouldprovide a high friction grip to the wheel. A device of this type isshown in U.S. Pat. No. 1,947,462 to Doorbar.

Other multiple component designs have been proposed for model trains toprovide for electrical insulation between the tracks and wheel bodies. Adevice of this type is shown in U.S. Pat. No. 2,558,384 to Pritchard.

In recognition of the short comings of roller coaster wheels withurethane treads which require frequent replacement and maintenance, asplit wheel construction has been proposed for sandwiching a rimtherebetween for mounting a urethane tire to thereby reduce the laborintensive process of repairing the wheels. A device of this type isshown in U.S. Patent Application No. 2003/0205909 to Bradley.

Large diameter railroad wheels are typically constructed of steel andare relatively expensive to replace. Thus, it has been proposed to, whena railroad wheel become worn or out of round, to machine the exteriorsurface thereof and, to anodize the surface and apply a steel ring tothe machined wheel to thus simulate the flanged exterior diameter of anew wheel. A device of this type is shown in U.S. Patent Application No.2009/0218837 to Mantkowski.

Aluminum roller coaster wheels have been proposed for both the weightbearing function as well as guiding of roller coaster itself. It hasbeen recognized that, particularly with respect to the guide wheels, thewheels are disengaged from contact with the guide rail and may thus slowdown in their rotation or come into a complete stop such that when thefast moving roller coaster carries the non-rotating wheel into contactwith a guide rail, high angular acceleration is experienced as wellskidding engagement with the rail thus severely limiting the life of thewheel. In effort to reduce the attendant shock and noise it has beenproposed to provide the wheels with a tread of plastic. A wheel of thistype is shown in U.S. Pat. No. 6,093,266 to Mollee.

Steel wheels remain popular today. It is believed that these steelwheels, because of their geometry and material characteristics, are veryeffective emitters of high frequency sound and are the source of severesqueal noise, a noise associated with a complex combination of creepagebetween the wheel and track and a mechanism known in the art as“stick-slip”. Stick-slip occurs when the process of creepage overcomesthe ability of a wheel-rail at the interface to impart rotation at thespeed of travel and the wheel ends up sliding relative to the rail ortrack. The friction between the wheel and rail tends to resiststick-slip but, when the friction is overcome and the lateral movementof the wheel relative on the flat top surface of the rail occurs, energyis released as a high pitched noise and the process then starts overagain. This rapidly oscillating wheel-rail contact force can excitevibration of the central portion of the wheel which then radiates a highpitch squeal. This, plus the mass of a steel wheel which imparts highforces with high angular acceleration tends to limit service life, posea danger from breakage and contribute to noise pollution.

SUMMARY OF THE INVENTION

The combination roller coaster wheel of the present invention includes alightweight alloy wheel body circumscribed by a hard tread ring, theinterfaces between the two being machined for a close fit and the ringbeing thermally shrink fit on the body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a combination roller coaster wheelincluding a lightweight wheel body circumscribed by a hard metal treadring embodying the present invention;

FIG. 2 is a elevation side view thereof;

FIG. 3 is an end view, in enlarged scale;

FIG. 4 is a detailed sectional perspective view depicting the tread ringbeing cut from the wheel body;

FIG. 5 is a detailed sectional view similar to FIG. 4 but showing thetread ring severed;

FIG. 6 is an end view similar to FIG. 3 but showing the severed treadring being separated;

FIG. 7 is a diametrical sectional view of a wheel body and tread ringwith the tread ring heated and the wheel body frozen for joining;

FIG. 8 is a detailed sectional view taken from the oval number 8 in FIG.7, in enlarged scale;

FIG. 9 is a diametrical sectional view similar to FIG. 7 but showing thewheel body and tread ring being pressed axially together;

FIG. 10 is a diametrical sectional view of the combination rollercoaster wheel shown in FIG. 8 returned to atmospheric temperatures; and

FIG. 11 is a flow chart showing a method of making the roller coasterwheel depicted in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1, 7 and 11, the method of the present inventioninvolves selection 51 of a wheel body 25 constructed of a lightweightwheel such as an aluminum alloy or urethane, machining 53 the peripherywith the major predetermined diameter to provide a tread bearing disk 27and machining along one axial side thereof a minor predetermineddiameter to form an open side annular stop notch 29. An endless treadring 31 is selected 55 of wear resistant material such as a carbon steelalloy and machined 57 on its interior to form a tread rim 33 having amajor diameter which is, at atmospheric temperature, smaller than themajor predetermined diameter of the disk 47 and machining at one sidewith a minor diameter forming a reduced in diameter stop flange 35 to bereceived in the stop notch 29. In the preferred embodiment the wheelbody 25 is subjected coolant such as for example a cryogen; dry ice orthe like to extract heat 59 and shrink the diameter thereof and thetread ring 31 is heated 61 to expand the diameter thereof so that thering can be pressed 63 onto the wheel body and held in place as shown inFIG. 9 while the components return to atmospheric temperature 65 and thecorresponding diameters to form a shrink fit stress bond at theinterface.

Steel roller coaster wheels are relatively expensive to manufacture andare lacking in ductility thus being particularly vulnerable to fatigueand failure resulting from the high impact loads and repetitive rapidacceleration loads attendant use, particularly of the guide wheels ofthe roller coaster. On the other hand, more ductile metal such asaluminum, fails to provide resistance to wear resulting from rolling andskidding contact with the roller coaster track throughout what cansometimes be thousands of feet of travel during each ride, which may berepeated six to twenty or more times every hour for twelve hours per dayduring times of heavy use. Thus, the labor and material costs forreplacement and repair of roller coaster wheels is a major part of thecost of operating a roller coaster. It is this problem to which thepresent invention is directed.

The wheel body 25 may be constructed of any lightweight material such asurethane or one of various aluminum alloys well-known to those skilledin the art and may exhibit some degree of ductility to absorb shockloads. For my preferred embodiment I have selected an aluminum alloy.

To provide for relatively inexpensive assembly and a high integrityjoint between the wheel 25 and ring 31, it is desirable to provideshrink-fitting of the endless ring 31 onto the wheel body to provide fora strained and strong joint between the two.

The wheel may be constructed, for instance, a relatively ductilealuminum alloy. The periphery of the wheel body will then be machined toa predetermined major diameter to provide the tread support disk 27 anda minor diameter at 29 to provide the annular notch having an axiallyfacing stop shoulder 41 to engage the flange 35. As will be appreciatedby those skilled in the art, the axial indexing function may be achievedby any one of a number of abutment configurations such as a frustoconical configuration for the interface between the tread ring and wheelbody such that when the cooperating conical surfaces seat against eachother the ring is properly indexed axially relative to the body.

In a preferred embodiment, an axial extending radially outwardly openingclearance groove 43 is formed in the rim 27 and notch 29 to provide forclearance of a cutting tool 45 (FIG. 4) to facilitate severance of thering for replacement purposes.

The tread ring 31 may be constructed of, for instance, a carbon steelalloy 4140 to provide a sturdy, load carrying tread ring contacting therail and exhibiting resistance to the wear as will be experienced fromrolling and skidding contact with the underlying roller coaster track.The ring 31 is machined on its interior to provide an inside diameterfor the rim 33 having a diameter at room temperature, smaller than theroom temperature diameter of the disk 27 and to likewise provide theinside diameter of the flange 35 with a diameter smaller than theoutside diameter of the annular notch 29. In some instances, only one orthe other of the diameters of the rim 33 or flange 35 are smaller atroom temperature than the corresponding diameters of the wheel.

Once the wheel body and tread ring have been machined, the wheel body 25may be chilled 59 as by application dry ice liquid nitrogen or one ofthe other cryogens to substantially reduce the temperature belowatmospheric temperature to thereby shrink the diameter of the wheelbody. Concurrently, or alternatively, the tread ring 31 may be heated 61as by oven heating or induction heating or the like to expand thediameter thereof so that the inner diameter of the rim and flange 33 and35, respectively are larger than the diameters of the disk 27 and notch29 to thereby allow for telescopical fitting of the ring axially ontothe wheel body 25 as shown in FIGS. 7 and 9. With the components alignedaxially the press platen 53 may be lowered to press 63 the ring axiallyonto the body until the annular shoulder of the flange 35 abuts theconfronting annular shoulder 41 of the notch 29 to exactly center thering on the body of the as shown in FIGS. 8 and 9 and hold thecomponents together while they return to atmospheric temperature 65 sothe ring will shrink onto the circumference of the expanding wheel body.As will be appreciated by those skilled in the art, the high stressesgenerated by the resultant thermal lock will thus be evenly distributedover the axial extent of the interface for even loading to maintain thering centered on the wheel body to thus cooperate in carrying the loadand shock during the service life of the wheel. The wheel device 19 maythen be removed from the press and is ready for mounting to the axial ofa roller coaster car.

Through empirical testing it has been proven that the combination rollercoaster wheel 19 has a service life extending well beyond that ofconventional steel or aluminum roller coaster wheels. In any event,after long usage, the ring will become worn thus requiring replacement.Such ring may easily be removed from the wheel body 25 by severing thering along the axial line of the clearance groove 43 (FIGS. 6 and 7) sothat ring may be bent away from the periphery of the wheel body as shownin FIG. 6. A new endless ring 31 may then be applied to the wheel body25 as described above with relation to FIGS. 7-11. The replacementprocess is efficient, straight forward and provides for a high integritybond between the replacement ring and wheel body.

For my exemplary embodiment, I have constructed the wheel body ofaluminum bar 6061-T6 and the tread ring 31 of 4140Q&T carbon alloytubing per ASTM A519. I have constructed the outside diameter of the rimring at 9.00 inches. For the shrink fit, I have constructed thepredetermined major diameter for the wheel body 27 at 8.3478 to 8.346inches and the minor predetermined diameter for the annular stop notch29 at 8.2570 to 8.258 inches correspondingly, I have constructed theinside diameter of the rim 33 at 8.3300 to 8.3320 inches and the insidediameter of the flange 35 from 8.2500 to 8.2518 inches. I havediscovered by making the inside diameter of the tread ring 31approximately 0.182% smaller than that of the outside diameter of thewheel body at atmospheric temperature I provide the satisfactory stressbond for the roller coaster wheels.

As will be appreciated by those skilled in the art other lightweightmaterials might be used for the wheel body and many other wear resistantmetals will serve the purpose of the tread ring shrunk fit onto thebody, it only being important that the body be lightweight and the ringof a hard metal and that the stress bond between the two be strong andresistant to shock and repetitive flex.

In operation, it will be appreciated that, for example, when thecombination wheel 19 of the present invention is utilized as a guidewheel for roller coasters, and the non-rotating wheel is carried at highvelocity into engagement with a guide rail, it will subject the surfaceof the tread ring 31 into what is first skidding contact, and thenrotating contact to initiate rotation thereof to thereby provide highangular acceleration as the surface of the ring skids along the rail andis brought up to speed rotating at high rpm's. It will be appreciatedthat the steel ring 31 will resist wear from the skidding contact aswell as any abrasive effect resulting from dirt or grit on the siderail. More importantly, it will be appreciated that even as the wheelbody is subjected to high angular acceleration its relatively lowdensity aluminum mass will minimize the resultant angular momentum thusminimizing the consequent stress to thus minimize the resultant rate offatigue for the metal. Also, it is believed that the level of noiseemitted from the vibration of the body of the wheel during creep skid isreduced from what would be emitted from a steel body of comparable sizeand shape.

Similarly, for the load bearing roller coaster wheels, the wheels 19will operate in carrying the load of the roller coaster train as ittravels along thousands of feet of rail often carrying up to twentypassengers or even more subjecting the wheel to high loads as itmaneuvers along the undulations and slopes in the track, around curvesand contacts with irregularities and undulations in the rail thussubjecting the ring 31 and wheel body 25 to shock loads, loads whichwill tend to be somewhat dissipated in the ductile characteristics ofthe wheel body which will tend to absorb a certain amount of shockbetween the ring and axle of the roller coaster. This tends to reducethe rate at which wheels are fatigued and prolongs the life over whatwould be the case for an integral steel wheel. Of even greaterimportance is that the subject wheels, being of much lighter weight thansteel wheels, serve to reduce the weight of the overall roller coastertrain and consequent magnitude of weight and attendant shock forcesapplied during travel over undulating tracks at high rates of speed.

As will be appreciated by those skilled in the art, the combinationroller coaster wheel of the present invention provides a significantreduction in weight for a roller coasters trains, a factor ofsignificant importance for a train requiring some 80 to 100 to therebyreduce the wear and tear on the roller coaster tracks. The combinationwheel provides the benefits of a lightweight aluminum which is a lessefficient transmitter of high frequency sound than steel and renders thetask of changing wheels much more convenient with less risk of physicalinjury to the workman by repeatedly lifting comparatively heavy steelwheels. Such wheels with diameter of 6 to 9 inches have proven farsuperior to prior art roller coaster wheels exhibiting a long servicefree life.

It will thus be appreciated that the combination roller coaster wheel ofthe present invention substantially reduces the weight of a multiple carroller coaster train, reduces the strain from rapid angular accelerationof the wheel, absorbs shock, and resists denting and wear whileminimizing emission of squeal noises from creep.

1.-26. (canceled)
 27. A roller coaster wheel comprising: a one piececircular aluminum alloy wheel body with a machined outside wheel bodyconfigured to, at atmospheric temperatures, provide predetermined majorand minor diameters forming a support disk of the predetermined majordiameter and formed along one axial edge with an annular stop notch ofthe predetermined minor diameter and further formed with a single stopshoulder facing in one axial direction; a carbon steel tread ringconfigured with a machined inside surface with, at atmospherictemperatures, an inside major diameter smaller than the predeterminedmajor diameter and a reduced-in-diameter flange of a minor insidediameter smaller than the predetermined minor diameter and furtherinclude an annular abutment surface abutted against the stop shoulder.28. The roller coaster wheel of claim 27 wherein: the inside surface ofthe tread ring is formed with the inside major diameter at atmospherictemperature tending to contract to a diameter substantially 0.182%smaller than the predetermined major diameter of the wheel.
 29. Theroller coaster wheel of claim 27 wherein: the tread ring is constructedof steel.
 30. The roller coaster wheel of claim 27 wherein: the ring isformed with the inside minor diameter, at atmospheric temperature,tending to contract to a diameter substantially 0.182% less than thepredetermined minor diameter.
 31. A roller coaster wheel comprising: aone piece aluminum alloy wheel body configured with, at atmospherictemperatures, an annular outside wheel body formed with predeterminedmajor and minor outside diameters forming a support disk of thepredetermined major diameter and formed along one axial edge of thesupport disk and annular stop notch of the predetermined minor diameterand further formed with a single stop shoulder facing in one axialdirection; a tread ring having a positive coefficient of thermalexpansion and constructed of a material harder than aluminum; the treadring being configured with an annular inner surface formed to, atatmospheric temperatures, tend to provide an annular rim having aninside major diameter smaller than the predetermined major diameter anda reduced-in-diameter stop flange of a diameter smaller than thepredetermined minor diameter and, further, formed with an annularsurface abutting the stop shoulder, the inside major and minor diametersbeing sufficiently smaller than the respective predetermined major andminor diameters to cause the ring to, when at atmospheric pressure, lockto the wheel body.
 32. A combination roller coaster wheel comprising: alightweight metal wheel body formed with an annular support surface of apredetermined major diameter and further configured with an annular stopnotch of a predetermined minor diameter smaller than the predeterminedmajor diameter and further formed with a single stop shoulder facing inone axial direction; a relatively hard, wear resistant, endless metaltread ring thermally shrink fitted on the wheel body and including anannular rim pressed against the major diameter of the wheel body and areduced in diameter stop annular flange received in the stop notch andfurther including an annular abutment surface abutting the stop surface.33. The combination roller coaster wheel of claim 32 wherein: the wheelbody is one piece.
 34. The combination roller coaster wheel of claim 32wherein: the wheel body is constructed of aluminum.
 35. The combinationroller coaster wheel of claim 32 wherein: the tread ring is constructedof steel.
 36. The combination roller coaster wheel of claim 33 wherein:the wheel body is constructed of aluminum.
 37. The combination rollercoaster wheel of claim 33 wherein: the tread ring is constructed ofsteel.
 38. A method of making a combination roller coaster wheelincluding: selecting a light weight metal wheel body; machining theannular outside of the wheel body to, at atmospheric temperatures,provide a predetermined diameter and an annular stop notch forming asingle stop shoulder facing in one axial direction; selecting a treadring of a material having a positive coefficient of thermal expansionand harder than the wheel body; machining the inside surface of thetread ring to provide, at atmospheric temperatures, a machined insidediameter defining an annular rim having an inside diameter sufficientlysmaller than the predetermined diameter to, at atmospheric temperature,lock on the predetermined diameter and further forming an axially facingannular surface to, when the ring is mounted to the wheel body, abut thestop shoulder, applying sufficient heat to the ring to expand the treadring or removing sufficient heat from the wheel body to shrink the wheelbody to render the inside diameter of the ring larger than thepredetermined diameter of the wheel to establish a radial clearancebetween the wheel body and ring; while maintaining the clearance,fitting the tread ring axially onto the wheel body to abut the annularsurface against the stop shoulder; and returning the wheel body and ringto atmospheric temperature to shrink fit the tread ring onto the wheelbody to lock the ring to the wheel body.
 39. The method of claim 38wherein: the step of selecting a lightweight metal wheel body includesselecting a wheel body of aluminum.
 40. The method of claim 38 wherein:the step of selecting the ring includes selecting a ring constructed ofsteel.
 41. The method of claim 38 wherein: the step of selecting thewheel body includes selecting a wheel body constructed of 6061-T6Aluminum.
 41. The method of claim 38 wherein: the step of selecting thering includes selecting the ring constructed of carbon alloy tubing perASTM A 519.